cult stage in the entire production
process: printing the cans. First, a
basecoat (a sort of primer paint) is
applied to the cans. Then the cans
move at very high speed past the rol
ler with the printing plates and an
ingenious system makes sure that the
can revolves at exactly the same
speed as the rollers.
The printing of cans is becoming
increasingly more important and tric
kier, according to Hermans. 'The
number of colours is increasing,
quality requirements are getting ever
more demanding and tolerances tight
er.' This is a challenge for CCE which
- just like itk customer - adopts the
principle that the image of the can
must project the quality of its con
tents.
'Necking-in'
After printing comes the third
complicated stage in the process:
'necking-in'. At the top of the can the
diameter is reduced and at the same
time a flange is formed. The lid is
seamed onto this flange after the can
has been filled.
Inspection of the cans after 'neck
ing-in' is very important because irre
gularities may occur in the material
during this process and this can cause
problems during filling.
Lacquering
Once the can has taken on its final
shape it is given a coating of lacquer
on the inside. The operation looks
simple, as the can revolves quickly
around its axis for a moment and a
Can Europe will be reducing that to
0.28 mm and its aim for the future is
to achieve 0.27 mm and less.
Seemingly minute differences, but
they have big technical consequences
for the process known as 'wall-iron
ing', one of the most difficult aspects
of can manufacture. In this process
the upright wall of the cup is 'ironed
out' until it has been stretched to the
right height and thickness. The mid
dle section of the can-to-be has a
'thickness' of 0.08 mm, but the top
section in turn is not allowed to be
thinner than 0.15 mm. 'Heineken fills
its cans at a pressure of 6 bar, so we
have to ensure during our develop
ment work that the strength and sta
bility of the can is maintained.'
Tolerances
After 'wall-ironing' the top edge of
the can is neatly cut off at the exact
height and the can is then thoroughly
washed. Then comes the second diffi-
